1. Field of the Invention
The present invention relates to a plasma display panel driving method and a plasma display apparatus in which an address discharge is generated by outputting an address pulse from an address electrode driving circuit.
2. Description of the Related Art
Conventionally, as an effective energy collecting method for an integrated circuit which needs high voltage operations such as a driver integrated circuit of a plasma display apparatus, an energy collecting circuit of a charge sharing system has been known.
As the energy collecting circuit of the charge sharing system, for example, a circuit is well known that includes a pull-up element and a pull-down element connected to an output terminal, an energy collecting capacitor, and a switching element connected between the energy collecting capacitor and the output terminal. In the energy collecting circuit of the charge sharing system, a power source voltage terminal, the pull-up element, the output terminal, the pull-down element, and a ground terminal are connected in order in a totem pole shape, and the energy collecting capacitor is connected to the output terminal via the switching element.
An example of the operations of the energy collecting circuit of the charge sharing system is described. When the voltage of the output terminal rises from ground potential to a power source voltage, the switching element is turned ON while the pull-up element and the pull-down element are OFF, and the voltage of the output terminal is raised by the electric charges stored in the energy collecting capacitor. Then the voltage of the output terminal has risen to a predetermined intermediate voltage, the switching element is turned OFF and the pull-up element is turned ON, and the voltage of the output terminal is clamped to be the power source voltage. On the other hand, when the voltage of the output terminal falls from the power source voltage to ground potential, the switching element is turned ON while the pull-up element and the pull-down element are OFF, and the voltage of the output terminal is lowered by storing electric charges in the energy collecting capacitor. Then the voltage of the output terminal falls to the predetermined intermediate voltage, the switching element is turned OFF and the pull-down element is turned ON, and the voltage of the output terminal is clamped to be ground potential.
For example, when the energy collecting capacitors of adjacent address pulse outputting circuits of the plasma display panel can be connected to be a short circuit, electric charges stored in the energy collecting capacitors can be shared between the adjacent address pulse outputting circuits. That is, the stored electric charges can be shared in all of the address electrode driving circuits. With this, energy saving can be performed (see Japanese Laid-Open Patent Publication No. 2005-210119: Patent Document 1).
In the energy collecting circuit of the charge sharing system, periods are required for increasing to the predetermined intermediate voltage and for decreasing to the predetermined intermediate voltage. Therefore, a generating time of the address pulse becomes long. On the other hand, a high-definition and high-brightness plasma display panel has been required, and the generating time of the address pulse (address time) is required to be short. In order to achieve the above, for instance, the address time is shortened by making the shifting time to the power source voltage or ground potential shorter than the charging (increasing)/discharging (decreasing) time to/from the predetermined intermediate voltage.
FIG. 8 is a diagram showing a voltage transition of an address pulse with the passage of time in a conventional charge sharing system. In FIG. 8, an intermediate voltage VDH/2 is supplied to an address electrode by the charge sharing system in MODE 1, a power source voltage VDH is supplied to the address electrode by clamping the power source voltage VDH in MODE 2, the intermediate voltage VDH/2 is supplied to the address electrode by the charge sharing system in MODE 3, and ground potential is supplied to the address electrode by clamping ground potential in MODE 4. In this, in order to shorten one address pulse period, it is determined that the fall time in MODE 4 is to be shorter than the fall time in MODE 3.
However, in the electrode driving circuit of Patent Document 1, since the plasma display panel has capacitive loads, when a voltage applied to an electrode has a steep change, this steep change influences other electrodes and a large voltage change is generated in the other electrodes.
FIG. 9 is an equivalent circuit of a discharge cell Cnm of a plasma display panel. In FIG. 9, when an address discharge is generated in the discharge cell Cnm at a position where a scan electrode Yn of an nth row crosses an address electrode Am of an mth column, a negative scanning pulse is applied to the scan electrode Yn and a positive address pulse is applied to the address electrode Am, so that the address discharge is generated in a capacitive load Cay. As shown in FIG. 9, in the discharge cell Cnm of the plasma display panel, in addition to the capacitive load Cay, a capacitive load Cax is formed between the address electrode Am and the sustain electrode Xn, and a capacitive load Cxy is formed between the sustain electrode Xn and the scan electrode Yn. That is, a capacitive coupling is formed in the discharge cell Cnm. Therefore, when a voltage to be applied to the address electrode Am has a steep change, this steep change causes a large voltage change in the sustain electrode Xn and the scan electrode Yn.
For example, when a fall of an address pulse of an address electrode Am at a scanning timing is steep, voltages to be applied to a sustain electrode Xn and a scan electrode Yn are changed, and these voltage changes promote a defect in generating a wall electric charge at an address discharge of the next scanning timing. When a sufficient wall electric charge is not generated at the address discharge, a sustain discharge is not suitably performed, and there is a risk that a discharge cell Cnm will not be capable of emitting light.